Carburetor



Dec. l, 195? w. J. LINDSTEADT CARBURETOR 2 SHEETS-SHEET l Filed Dec. 30,194'? T m m m D l im. a w N ,Q @I J. n N. wm S N. m- Uv' R MB Nw/l NM.#y uw w QQ QQ W a Q n f ,www f M NN@ J; Nw Q\\ m .ww WQ |:ll QN Qw Nm, QQM.

ATTORNEY Dec. 16, 1952 w. J. LINDSTEADT cARBUREToR Filed Dec. 3Q, 1947 2SHEETS-SHEE 1' 2 M w mwMI/m//w/ W. -\\.||il Effi 0 mun w.. \gf//wl: l L.`f/// NW N "v v4 9, .1. A M\ h a J.. 1 Z T 1 X .Will/61. M 0 l wwwwwmwwa 4 .e J 7.. M. o 4 y w M a 00 //MM M M V@ a/o 0 4 v 2 5 am A M a. Y,YYIIIHIIIHHHIIM Il|| L Patented Dec. 16, 1952 UNITED STATES PATENTFFICE 2,621,911y cAiiBUREToR waiter i. Lindstea'dt, Mount. Clemens,Milch., as, signor to Bendix AviationI Corporation, South Bend, Ind., acorporation of Delaware Application December 30, 1947, Serial No.794,532

(C1. zei-41) 11 Claims. l

The present invention relates to charge forming devices, and moreparticularlyV to carburetors for internal combustion engines.

One of the principal objects of the present invention is to provide acarburetor for an internal combustion engine which is adapted tominimize backiiring in the eYhaust pipe and mufliei' when the engine isdecelerated.

Another object of the invention is to provide a fuel system in acarburetorfor' forming a combustible mixture during the entire time theengine is operating with the throttle valve in closed or in nearlyclosed position. Y

Another object of the invention is to provide a means in an enginecarburetor for enriching the idle mixture while the engine isdecelerating.

Further objects and advantages of the invention will be apparent fromthe following description and accompanying drawings, wherein two specicembodiments of my invention are disclosed. In the drawings:

Figure l is a Vertical cross-section' ofA a carburetor showing some ofthe elements thereof rearranged to more clearlyshow their operativerelationship Figure 2 is a vertical cross-sectonof a portion of thecarburetor shown in Figure l;

Figure 3 is another vertical cross-section of the portion shown inFigure 2; o

`Figure 4 is a vertical cross-section of amo'dication of the invention;and o Figure 5 is a vertical cross-section of a portion of thecarburetor shown in Figure 4.

Referring more specifically' to the drawings, in Figure l, numeral I0designates the induction passage of a downdraft carburetor'which' may beeither a single or doublebarrel type, numeral I2 an air inlet, Iii amixture outlet, IE a large venturi, I8 a small venturi, 20 a choke valvedisposed in the air inlet I2, and' 22 a throttle valve mounted on shaft24 in throttle'body 26. A fuel bowl 38 contains aiioat 32 mounted onfloat pivot 34 adjacent float needle valve assembly 36. The fuel isadmitted at the fuel inlet 38. and passes through screen d and valveassembly 36 into the fuel bowl. The fuel is delivered from the fuel bowlthrough the main dischargejet 50 which extends from a point" near thebottom of the fuel bowl to the throat' ofthe 'small venturi I8 andincludes a main. metering jet 52 and air inlet orifices 53 through whichair from the high speed air bleeder 54 is admitted. As the fuel passesfrom the fuel bowl through main charge jet, air from the high speedbleeder is 2 mixed' with said fuel, forming an emulsion which is`discharged into the throat of the small venturi;

An accelerating pump generally shown at 60 includes a manually'actuatedpiston I62 operated in cylinder 64 by the movement of the throttle valvethrough rod 66, lever 68 and a linkage not shown) connecting lever 68with the throttle valve actuating mechanism. The fuel for theaccelerating pump is drawn from the fuel bowl 38 through inlet passage'I8 and check Valve l2 into cylinder 64 beneath piston 62, and isdischarged through accelerating pump jet I4 into the inductionpassage'through a special jet (not shown).

During the operation of the engine at high speeds and under high poweroutput, an auxiliary fuel by-pass jet S0 controlled by a valve 8| isopened to admit additional fuel into the main discharge jet posterior tomain metering jet 52 forV enriching the fuel-air mixture delivered tothe engine. Valve 8| is opened in opposition to a spring 82bylreciprocable rod 83 actuated inthe direction to open said valve by aspring 84 and in the opposite direction by a vacuum piston 86 mounted incylinderv 88 at the upper end of said rod. Spring 84 reacts between aplate 90 mounted'on the lower end' of said rod and plug 82 inserted inthe lower end of cylinder 88. |The upper end of cylinder 88 is connectedby a conduit 94 with the, induction passage on the engine side of thethrottle valve so that manifold vacaum will hold piston 86 and rod' 83in the position shown in Figure 1 during idling and cruising. When thethrottle valve is opened for high speed or high power output, themanifold vacuum becomes insufcient to hold rod 83 in its lifted positionin opposition to spring 84 and thus permits rod 83 and' plate 98 to movedownwardly, opening valve 8l and admittingadditional fuel from the fuelbowl into the main discharge jet.

'When the throttle valve is in closedl ornearly closed position, theengine operates on the fuel supplied by the idle system consisting ofidle tube I I0, through which the fuel for idlingV ismetered,';horizontal conduit II2 and vertical conduit'v llt. The fuelisdischarged through ports IISV and I I8 above an'dbelow the throttlevalve, respectively, under0 certain idling conditions and only` throughport "I I8" under other idling conditions'. Whenthethrottle'.valveisi'closed orr substantially iclos'ed.the charge, i. e. the fuel-airjemulsion formed` in the idling systemfis discharged through port H8,and air is bled into the idle system through port I |6. As the throttlevalve is moved from closed position to a partly open position, the edgeof the throttle valve passes port H6 so that both ports H6 and |I8function as discharge ports for the idling mixture. An idle air bleed|26 at the upper end of vertical conduit ||4 and a secondary idle airbleed |22 near the lower end of conduit H4 supply air to the idle systemto form the fuel-air emulsion which is discharged through ports I |6 andI I8, as described. The quantity of fuel-air emulsion delivered to theengine is regulated by adjustable needle valve |24.

The present invention is primarily concerned with a means for preventingbackfiring in the exhaust pipe and muffler, which sometimes occurs whenthe throttle valve is closed while the vehicle is traveling at a ratherhigh rate of speed. This backiiring is principally caused by theformation of a mixture in the cylinders too lean to be ignited by thespark, and the passing of this lean mixture into the exhaust pipe andmuier where it is ignited by subsequent firing of the engine. The leanmixtures are usually produced by the return of exhaust gases from themanifold to the cylinders when the intake manifold vacuum is high. Thepresent invention overcomes the conditions producing the backring byproviding an additional quantity of fuel to enrich the fuel-air mixturesupplied the engine when the intake manifold vacuum is exceptionallyhigh. This enriched mixture remains a combustible charge even afterbeing diluted by the exhaust gases returned to the cylinders. Thisadditional fuel is supplied to the idling system through a cylindricalstem |30, horizontal conduit |32 and vertical conduit |34 whichcommunicates with vertical conduit H4 at port |36 near the centralportion of conduit H4. Cylindrical member includes a plurality of ports|46 which are below the level of the fuel in the fuel bowl, and a springloaded valve |42 which is actuated by an extension on plate 90 whenvacuum piston 86 is lifted to its uppermost position. Since thebackfiring occurs only when there is an extremely high manifold vacuumsuch as between 21 and 24 inches of mercury, this `auxiliary idlingsystem does not become operable until the high vacuum is reached. Thisis accomplished by including a spring |44 mounted on rod 83 andsupported by collar |46. This spring rides on rod 83 and functions as anabutment to determine the upper limit of the movement of rod 83 fornormal manifold vacuum. It is seen in Figure 3 that the extension onplate 9U has not engaged the stem of valve |42 so that said valveremains closed for normal manifold vacuum. When the manifold vacuumrises above a predetermined value, such as 21 inches 0f mercury, spring|44 becomes compressed, permitting the extension on plate 90 to openvalve |42 and thereby permit -additional fuel to flow into the idlingsystem through conduits |32 and |34. When the manifold vacuum againbecomes normal, spring 44 returns rod 83 and plate 90 to the positionshown in Figure 3, permitting valve |42 to close so that the idle systemagain functions normally. Should the manifold vacuum further decrease sothat spring 84 is able to overcome the effect of said vacuum on piston86, rod 83 and plate 90 are lowered to the position shown in Figure 2wherein power enrichment valve 80 is held open to permit additional fuelto pass into the main discharge jet.

In the modification shown in Figure 4, the

idling mixture is enriched for nign manifold vacuum operation by theclosing of the idle air bleed |20. This is -accomplished by a valve |60which is actuated by vacuum piston 86 through rod 83, plate 90, rod |62and pivoted lever |64. Spring |44 functions as an abutment for rod 83 toprevent plate 96 from engaging the lower end of rod |62 for normalengine operation, as shown in Figure 5. When plate is not in Contactwith rod |62, valve |66 is held in its open position, as shown in Figure5, by a relatively weak spring |66 mounted on rod |62 and reactingbetween a xed collar |68 and a portion of the fuel bowl cover. Theopening movement of valve |66 is limited by a set screw |70 whichfunctions as an abutment for one end of pivoted lever |64. When themanifold vacuum is too low to overcome the force of spring 84, plate 96engages the stern of valve 8) and opens said valve to permit additionalfuel to pass into the main discharge jet 50. As the manifold vacuum isincreased when the throttle valve is moved to closed position, piston 86is moved upwardly, carrying therewith rod 83 and plate S6, thusdisengaging said plate from the stem of valve 86 and permitting saidvalve to close. At this increased manifold vacuum, rod 83 and plate 90assume the position shown in Figure 5, wherein spring |44 is functioningas an abutment. Should the manifold vacuum rise above a predeterminedvalue, such as 2| inches of mercury, spring |44 is compressed,permitting the extension of plate 90 to engage the lower end of rod |62and move said rod and lever |64 in the direction to close valve |66. Thedecreased quantity of air thus admitted into the idling system causes anincrease in the richness of the idling fuel-air mixture delivered to theengine.

Many other arrangements of the two modifications disclosed herein may bemade to suit requirernents.

I claim:

1. In a fuel supply system for an engine having an induction passagewith a throttle valve therein, a source of fuel, a conduit connectingsaid source of fuel with the induction passage on the engine side of thethrottle valve for supplying said engine with fuel while the throttlevalve is in closed or nearly closed position, a passageway connectingsaid source of fuel with said conduit for admitting additional fuel intosaid conduit, and a valve mechanism in said passageway adapted to beopened in response to high manifold vacuum for controlling the flow offuel through said passageway.

2. In a fuel supply system for an engine having an induction passagewith a throttle valve therein, a source of fuel, a conduit connectingsaid source of fuel with the induction passage on the engine side of thethrottle valve for supplying said engine with fuel while the throttlevalve is in closed or nearly closed position, a metering restriction insaid conduit, a passageway connecting said source of fuel with saidconduit posterior to said restriction for admitting additional fuel intosaid conduit, and a valve mechanism in said passageway openable inresponse to high manifold vacuum for controlling the flow of fuelthrough said passageway.

3. In a fuel supply system for an engine having an induction passagewith a throttle valve therein, a fuel bowl, a conduit connecting saidfuel bowl with the yinduction passage on the engine side of the throttlevalve for supplying said engine with fuel while the throttle valve is inclosed or nearly closed position, a metering restriction in saidconduit, a passageway connecting said fuel bowl with said conduitposterior to said restriction for admitting additional fuel into saidconduit, and a valve mechanism in said passageway adapted to be openedonly in response to high manifold vacuum for controlling the flow offuel through said passageway.

Li. In a carburetor for an internal combustion engine, an inductionpassage, a throttle valve in said induction passage, a source of fuel, amain fuel conduit connecting said source of fuel with said inductionpassage, a power enrichment jet connecting said source of fuel with themain fuel conduit, a valve for controlling said jet, an idle systemincluding a conduit connecting the source of fuel with the inductionpassage on the engine side of the throttle valve, a fuel passagewayconnecting the source of fuel with the idle system conduit, a valvemechanism in said passageway, and a pressure responsive spring-loadedmeans adapted to open the power enrichment valve when the manifoldvacuum is low and to open the passageway valve when the manifold vacuumis high.

5. In a carburetor for an internal combustion engine, an inductionpassage, a throttle valve in said induction passage, a fuel bowl, a mainfuel conduit connecting said fuel bowl with said induction passage, apower enrichment jet connecting said fuel bowl with the main fuelconduit, a valve for controlling said jet, an idle system including aconduit connecting the fuel bowl with the induction passage on theengine side of the throttle valve, a metering restriction in said idlesystem conduit, a fuel passageway connecting the fuel bowl with the idlesystem conduit posterior to said restriction, a valve mechanism in saidpassageway, and a pressure responsive springloaded means adapted to openthe power enrichment valve when the manifold vacuum is low and to openthe passageway valve when the manifold vacuum is high.

6. In a fuel supply system for an engine having an induction passagewith a throttle valve therein, a source of fuel, a conduit connectingsaid source of fuel with the linduction passage on the engine side ofthe throttle valve for supplying said engine with fuel while thethrottle valve is in closed or nearly closed position, an air bleed forsaid conduit, and a valve mechanism actuated in response to highmanifold vacuum for controlling said air bleed.

7. In a fuel supply system for an engine having an induction passagewith a throttle valve therein, a fuel bowl, a conduit connecting saidfuel bowl with the induction passage on the engine side of the throttlevalve for supplying said engine with fuel while the throttle valve is inclosed or nearly closed position, a metering restriction in saidconduit, an air bleed for said conduit posterior to said restriction,and a valve mechanism actuated in response to high manifold vacuum forclosing said air bleed.

8. In a carburetor for an internal combustion engine, an inductionpassage, a throttle valve in said induction passage, a fuel bowl, a mainfuel conduit connecting said fuel bowl with said induction passage, apower enrichment jet connecting said fuel bowl with the main fuelconduit, a valve for controlling said jet, an idle system including aconduit connecting the fuel bowl with the induction passage on theengine side of the throttle valve, an air bleed for said idle systemconduit, and a pressure responsive spring loaded means adapted to openthe power enrichment valve when the manifold vacuum is low and to closethe idle air bleed valve when the manifold vacuum is high.

9. In a fuel system for an engine having an induction passage with athrottle valve therein: a fuel bowl, a passageway for deliveringfuel-air emulsion to the induction passage on the engine side of thethrottle valve, said passageway having two branch conduits, one forconnecting said passageway to said fuel bowl and the other forconnecting said passageway to a source of air, and a valve mechanism inone of said conduits actuated only in response to a higher manifoldvacuum than exists during normal engine idling for enriching thefuel-air emulsion supplied by said passageway to the induction passage.

l0, In a fuel system for an engine having an induction passage with athrottle valve therein: a source of fuel, a passageway for deliveringfuelair emulsion to the induction passage adjacent the throttle valve,said passageway having two branch conduits, one for connecting saidpassageway to the source of fuel and the other for connecting saidpassageway to a source of air, and a valve mechanism in one of saidconduits actuated only in response to a higher manifold vacuum thanexists during normal engine idling for enriching the fuel-air emulsionsupplied by said passageway to the induction passage.

11. .An idle fuel system in a carburetor having an induction passagewith a throttle valve therein comprising: a source of fuel, a passagewayfor delivering fuel-air emulsion to the induction passage on the engineside of the throttle valve, said passageway having two branch conduits,one for connecting said passageway `to the source of fuel and the otherfor connecting said passageway to a source of air, and a valve mechanismin one of said conduits actuated only in response toa higher manifoldvacuum than exists during normal engine idling for enriching thefuel-air emulsion supplied by said passageway to the induction passage.

WALTER J. LINDS'IEADI.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,742,37 6 Beard Jan. 7, 19301,882,725 Asire Oct. 18, 1932 2,208,864 Farr July 23, 1940 2,209,511Coffey July 30, 1940 2,212,946 Mock et al Aug. 27, 1940 2,242,825 JonesMay 20, 1941

